Contrasting Developmental Trajectories in the Earliest Known Tetrapod Forelimbs

2009/04/16 by Viviane Callier, Jennifer A. Clack, Per Ahlberg · 5 citations
Earth and Planetary Sciences · Environmental Science · #Paleontology and Evolutionary Biology #Ichthyology and Marine Biology #Amphibian and Reptile Biology #Tetrapod (structure) #Ontogeny #Biology #Anatomy #Evolutionary biology #Forelimb #Zoology #Paleontology

paper · doi:10.1126/science.1167542

openalex publication_date 2009/04/16 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/23

Abstract

Ichthyostega and Acanthostega are the earliest tetrapods known from multiple near-complete skeletons, with Acanthostega generally considered the more primitive. New material indicates differing ontogenetic trajectories for their forelimbs: In Ichthyostega, the pattern of muscle attachment processes on small humeri (upper arm bones) resembles that in "fish" members of the tetrapod stem group such as Tiktaalik, whereas large humeri approach (but fail to attain) the tetrapod crown-group condition; in Acanthostega, both small and large humeri exhibit the crown-group pattern. We infer that Ichthyostega underwent greater locomotory terrestrialization during ontogeny. The newly recognized primitive characteristics also suggest that Ichthyostega could be phylogenetically more basal than Acanthostega.

Citations

• The Carboniferous amphibian Proterogyrinus Scheelei Romer, and the early evolution of tetrapods
• Early tetrapod relationships revisited
• Ventastega curonica and the origin of tetrapod morphology

Cited by

• Woodland Hypothesis for Devonian Tetrapod Evolution
• Biomechanics and functional preconditions for terrestrial lifestyle in basal tetrapods, with special consideration ofTiktaalik roseae
• Tetrapod trackways from the early Middle Devonian period of Poland
• Development and Evolution of the Muscles of the Pelvic Fin
• Tetrapod [wikipedia]

Related

• Digital volumetric modeling reveals unique body plan experimentation in the Devonian tetrapod Ichthyostega
• The Fin to Limb Transition: New Data, Interpretations, and Hypotheses from Paleontology and Developmental Biology
• Behavioral evidence for the evolution of walking and bounding before terrestriality in sarcopterygian fishes
• A Marine Stem-Tetrapod from the Devonian of Western North America
• Vertebral microstructure marks the emergence of pelagic ichthyosaurs soon after the End Permian Mass Extinction